Collaborative operation of software defined radios

ABSTRACT

A device includes circuitry configured to implement one or more PHY communications protocols to simultaneously communicate with one or more stations via communication links on one or more wireless networks, communicate with additional devices via a backhaul network, and exchange collaboration data, including at least one of protocol data or collaborative beamforming data, with the additional devices via the backhaul network to maintain signal parameters of communications signals with the one or more stations.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The present application claims the benefit of the earlier filing date ofU.S. provisional application 62/279,424 having common inventorship withthe present application and filed in the U.S. Patent and TrademarkOffice on Jan. 15, 2016, the entire contents of which being incorporatedherein by reference.

BACKGROUND

Technical Field

The present disclosure relates to software defined radio (SDR),specifically a device, system, and method for collaboratively operatingSDRs.

Description of the Related Art

Software defined radio (SDR) provides the opportunity to develop fullyprogrammable wireless communication systems, effectively supplantingconventional radio technologies, which typically have the lowestcommunication layers implemented in primarily in fixed, custom hardwarecircuits. In conventional radio implementations, as wirelesscommunication devices move from one location to the next, the devicesperform handoff procedures with access points to transfer controlbetween wireless access points. When errors occur during the handoffprocess, the devices lose access to the wireless communication network.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of this disclosure and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is an exemplary illustration of a software defined radio (SDR)architecture, according to certain embodiments;

FIG. 2 is an exemplary diagram of a hardware and logic configuration ofa computing device, according to certain embodiments;

FIG. 3 is an exemplary diagram of a radio controller and a RF front end,according to certain embodiments;

FIG. 4 is an exemplary diagram of a wireless communication system,according to certain embodiments;

FIG. 5 is an exemplary flowchart of a handoff prevention process,according to certain embodiments;

FIG. 6 is an exemplary diagram of a multi-protocol wirelesscommunication system, according to certain embodiments;

FIG. 7 is an exemplary diagram of a multi-input, multi-output (MIMO)wireless communication system, according to certain embodiments;

FIG. 8 is an exemplary flowchart of a MIMO modulation process, accordingto certain embodiments;

FIG. 9 is an exemplary diagram of a collaborative beamformingcommunication system, according to certain embodiments; and

FIG. 10 is an exemplary flowchart of a collaborative beamformingprocess, according to certain embodiments.

DETAILED DESCRIPTION

In the drawings, like reference numerals designate identical orcorresponding parts throughout the several views. Further, as usedherein, the words “a,” “an” and the like generally carry a meaning of“one or more,” unless stated otherwise.

In an exemplary implementation, a device includes circuitry configuredto implement one or more PHY communications protocols to simultaneouslycommunicate with one or more stations via communication links on one ormore wireless networks, communicate with additional devices via abackhaul network, and exchange collaboration data with the additionaldevices via the backhaul network to maintain signal parameters ofcommunications signals with the one or more stations.

In another exemplary implementation, a method includes implementing oneor more PHY communications protocols to simultaneously communicate withone or more stations via communication links on one or more wirelessnetworks; communicating with additional devices via a backhaul network;and exchanging collaboration data with the additional devices via thebackhaul network to maintain signal parameters of communications signalswith the one or more stations.

In another exemplary implementation, a device includes circuitryconfigured to modulate one or more coded spatial streams of a firstmulti-input, multi-output (MIMO) signal to a first station at a firstfrequency via one or more antennas, forward one or more additional codedspatial streams of the first MIMO signal at the first frequency toanother device via a backhaul network, and coordinate, with the anotherdevice, simultaneous transmission of a plurality of MIMO signals to aplurality of stations on a plurality of frequencies.

Aspects of the present disclosure are directed to collaborativeoperations of software defined radios (SDRs). In some implementations,the SDRs are included in access points for multiple wirelesscommunication networks and can be used to replicate one PHY protocolsthat are compatible with stations that include user equipment (UE), basestations, and the like so that station connections can be transferredbetween the access points without having to perform handoff procedures.In addition, SDRs can be included in access points having multipleantennas in order to perform in multi-input, multi-output (MIMO)communications with less hardware than conventional implementations dueto frequency sharing between the SDRs. In other aspects, SDRs inmultiple access points can perform collaborative beamforming to cancelblockers from received signals so that less complex and less costlyhardware can be used in transceivers of the access points.

Implementations disclosed herein present a fully programmable softwaredefined radio (SDR) platform and system able to be implemented ongeneral-purpose computing devices, including personal computer (PC)architectures. Implementations of the SDR herein combine the performanceand fidelity of general-purpose processor (GPP) SDR platforms. Inaddition, implementations of the SDR herein may use both hardware andsoftware components and techniques to perform the processes describedherein.

FIG. 1 illustrates an exemplary architecture of an SDR platform andsystem 100 according to some implementations herein. The SDR platformand system 100 includes one or more processors 102 that may bemulti-core processors according to some implementations. Each core 104includes one or more corresponding onboard local caches 106 that areused by the corresponding 104 during processing. Additionally, theprocessor 102 may also include one or more shared caches 108 and a businterface 110. Examples of suitable multi-core processors include theXenon™ processor available from Intel Corporation of Santa Clara,Calif., USA, and the Phenom™ processor available from Advanced MicroDevices of Sunnyvale, Calif., USA, although implementations herein arenot limited to any particular multi-core processor. In addition, theprocessor 102 may be reprogrammable hardware such as Field ProgrammableGate Arrays (FPGA), or even dedicated hardware engines. In one exampleillustrated, one or more cores can be allocated for performingprocessing for the SDR, while other remaining cores can performprocessing for other applications, the operating system, or the like.Further, in some implementations, two or more processors 102 can beprovided, and cores 104 across the two or more processors 102 can beused for SDR processing. Throughout the disclosure, the processors 102can interchangeably be referred to as processing circuitry or circuitry.

The processor 102 is in communication via bus interface 110 with ahigh-throughput, low-latency bus 112, and thereby to a system memory114. The bus 112 may be a PCIe bus or other suitable bus having a highdata throughput with low latency. Further, the bus 112 is also incommunication with a radio controller 116. As is discussed fluffierbelow, the radio controller 116 may be coupled to an interchangeableradio front end (RF front end) 118. The RF front end 118 is a hardwaremodule that receives and/or transmits radio signals through an antenna(not shown in FIG. 1). In some implementations of the SDR architectureherein, the RF front end 118 represents a well-defined interface betweenthe digital and analog domains. For example, in some implementations,the RF front end 118 may include analog-to-digital (A/D) anddigital-to-analog (D/A) converters, and necessary circuitry for radiofrequency transmission, as is discussed further below.

During receiving, the RF front end 118 acquires an analog RF′ waveform120 from the antenna, possibly down-converts the waveform to a lowerfrequency, and then digitizes the analog waveform into discrete digitalsamples 122 before transferring the digital samples 122 to the radiocontroller 116. During transmitting, the RF front end 118 accepts astream of software-generated digital samples 122 from a software radiostack 124 (i.e., software that generates the digital samples, asdiscussed below), and synthesizes the corresponding analog waveform 120before emitting the waveform 120 via the antenna. Since all signalprocessing is done in software on the processor 102, the design of RFfront end 118 can be rather generic. For example, the RF front end 118can be implemented in a self-contained module with a standard interfaceto the radio controller 116. Multiple wireless technologies defined onthe same frequency band can use the same RF front end hardware 118.Furthermore, various different RF front ends 118 designed for differentfrequency bands can be coupled to radio controller 116 for enablingradio communication on various different frequency bands. Therefore,implementations herein are not limited to any particular frequency orwireless technology.

According to some implementations herein, the radio controller 116 is aPC interface board optimized for establishing a high-throughput,low-latency path for transferring high-fidelity digital signals betweenthe RF front end 118 and memory 114. The interfaces and connectionsbetween the radio front end 118 and multi-core processor 102 can enablesufficiently high throughput to transfer high-fidelity digitalwaveforms. Accordingly, to achieve a predetermined system throughput,some implementations of the radio controller 116 use a high-speed,low-latency bus 112, such as PCIe. With a maximum throughput of 64 Gbps(e.g., PCIe x32) and sub-microsecond latency, PCIe is easily able tosupport multiple gigabit data rates for sending and receiving wirelesssignals over a very wide band or over many MIMO channels. Further, thePCIe interface is typically common in many conventional general-purposecomputing devices. The radio controller 116 can also be a dedicatedhardware bus connection, and may even be co-located with the processor102 and the RF front end 118.

One role of the radio controller 116 is to act as a bridge between thesynchronous data transmission at the RF front end 118 and theasynchronous processing on the processor 102, The radio controller 116implements various buffers and queues, together with a large onboardmemory, to convert between synchronous and asynchronous streams and tosmooth out bursty transfers between the radio controller 116 and thesystem memory 114. The large onboard memory further allows caching ofpre-computed waveforms for quick transmission of the waveforms, such aswhen acknowledging reception of a transmission, thereby addingadditional flexibility for software radio processing.

In addition, the radio controller 116 provides a low-latency controlpath for software to control the RF front end hardware 118 and to ensurethat the RF front end 118 is properly synchronized with the processor102. For example, wireless protocols have multiple real-time deadlines.Consequently, not only is processing throughput a critical requirement,but the processing latency should also meet certain response deadlines.For example, some Media Access Control (MAC) protocols also requireprecise timing control at the granularity of microseconds to ensurecertain actions occur at exactly pre-scheduled time points. The radiocontroller 116 of implementations herein also provides for such lowlatency control.

FIG. 2 illustrates an exemplary depiction of a computing device 200 thatcan be used to implement the SDR implementations described herein, suchas the SDR platform and system 100 described above with reference toFIG. 1. In the implementations described further herein, the computingdevice 200 may be a wireless access point or mobile device that canimplement one or more wireless communication protocols, such as a basestation, switch, router, user equipment (UE), and the like. In addition,the terms computing device and SDR can be used interchangeablythroughout the disclosure.

The computing device 200 includes one or more processors 202, a memory204, one or more mass storage devices or media 206, communicationinterfaces 208, and a display and other input/output (I/O) devices 210in communication via a system bus 212. In addition, the computing device200 can also include one or more timer blocks 220 in order to provide anotion of time to the various components of the computing device 200.Memory 204 and mass storage media 206 are examples of computer-readablestorage media able to store instructions which cause computing device200 to perform the various functions described herein when executed bythe processor(s) 202. For example, memory 204 may generally include bothvolatile memory and non-volatile memory (e.g., RAM, ROM, or the like).Further, mass storage media 206 may generally include hard disk drives,solid-state drives, removable media, including external and removabledrives, memory cards, Flash memory, or the like. The computing device200 can also include one or more communication interfaces 208 forexchanging data with other devices, such as via a network, directconnection, or the like, as discussed above. The display and otherinput/output devices 210 can include a specific output device fordisplaying information, such as a display, and various other devicesthat receive various inputs from a user and provide various outputs tothe user, and can include, for example, a keyboard, a mouse, audioinput/output devices, a printer, and so forth.

Computing device 200 further includes radio controller 214 and RF frontend 216 for implementing the SDR herein. For example, system bus 212 maybe a PCIe compatible bus, or other suitable high throughput, low latencybus. The radio controller 214 and the RF front end 216 may correspond tothe radio controller 116 and the RF front end 118 described previouslywith reference to FIG. 2, and as also described below, such as withreference to FIG. 3. Furthermore, a radio control module 218 can includesoftware instructions stored in memory 204 or other computer-readablestorage media for controlling operations on radio controller 214, as isdescribed additionally below. The computing device 200 described hereins only one example of a computing environment and is not intended tosuggest any limitation as to the scope of use or functionality of thecomputer architectures that can implement the SDR herein. Neither shouldthe computing device 200 be interpreted as having any dependency orrequirement relating to any one or combination of components illustratedin the computing device 200.

Furthermore, implementations of SDR platform and system 100 describedabove can be employed in many different computing environments anddevices for enabling a software-defined radio in addition to the exampleof computing device 200 illustrated in FIG. 2. Generally, many of thefunctions described with reference to the figures can be implementedusing software, hardware (e.g., fixed logic circuitry), manualprocessing, or a combination of these implementations. The term “logic”,“module” or “functionality” as used herein generally representssoftware, hardware, or a combination of software and hardware that canbe configured to implement prescribed functions. For instance, in thecase of a software implementation, the term “logic,” “module,” or“functionality” can represent program code (and/or declarative-typeinstructions) that perform specified tasks when executed on a processingdevice or devices (e.g., CPUs or processors). The program code can bestored in one or more computer readable memory devices, such as memory204 and/or mass storage media 206, or other computer readable storagemedia. Thus, the methods and modules described herein may be implementedby a computer program product. The computer program product may includecomputer-readable media having a computer-readable program code embodiedtherein. The computer-readable program code may be adapted to beexecuted by one or more processors to implement the methods and/ormodules of the implementations described herein. The terms“computer-readable storage media”, “processor-accessible storage media”,or the like, refer to any kind of machine storage medium for retaininginformation, including the various kinds of memory and storage devicesdiscussed above.

FIG. 3 illustrates an exemplary implementation of a radio controller 302and RF front end 304 that may correspond to the radio controller 116,214 and RF front end 118, 216 described previously. In the exampleillustrated, the radio controller 302 includes functionality forcontrolling the transfer of data between the RF front end 304 and asystem bus 306, such as buses 112, 212 discussed previously. In theillustrated implementation, the functionality is a field-programmablegate array (FPGA) 308, which may be a Virtex-5 FPGA available fromXilinx, Inc., of San Jose, Calif., USA, one or more other suitableFPGAs, or other equivalent circuitry configured to accomplish thefunctions described herein. The radio controller 302 includes a directmemory access (DMA) controller 310, a bus controller 312, registers 314,an SDRAM controller 316, and an RF controller 318. The radio controller302 further includes a first FIFO buffer 320 for acting as a first FIFOfor temporarily storing digital samples received from RF front end 304,and a second FIFO buffer 322 for temporarily storing digital samples tobe transferred to RF front end 304. The DMA controller 310 controls thetransfer of received digital samples to the system bus 306 via the buscontroller 312. SDRAM controller 316 controls the storage of data inonboard memory 324, such as digital samples, pre-generated waveforms,and the like.

The radio controller 302 can connect to various different RF front ends304. In some implementations, the RF front end 304 includes an RFcircuit 326 configured as an RF transceiver for receiving radiowaveforms from an antenna 328 and for transmitting radio waveforms viaantenna 328. The RF front end 304 further may include ananalog-to-digital converter (ADC) 330 and a digital-to-analog converter(DAC) 332. As discussed previously, analog-to-digital converter 330converts received radio waveforms to digital samples for processing,while digital-to-analog converter 332 converts digital samples generatedby the processor to radio waveforms for transmission by RF circuit 326.Furthermore, it should be noted that implementations herein are notlimited to any particular front end 304, and in some implementations,the entire front end 304 may be incorporated into the radio controller302. Alternatively, in other implementations, analog-to-digitalconverter 330 and digital-to-analog converter 332 may be incorporatedinto the radio controller 302, and RF front end 304 may merely have anRF circuit 326 and antenna 328. Other variations may also be apparent inview of the disclosure herein.

In the implementation illustrated in FIG. 3, the DMA controller 310 andbus controller 312 interface with the memory and processor on thecomputing device (not shown in FIG. 3) and transfer digital samplesbetween the radio controller 302 and the system memory on the computingdevice, such as memory 114, 204 discussed above. The radio controllersoftware control module 218 discussed above with reference to FIG. 2sends commands and reads radio controller states through radiocontroller registers 314. The radio controller 302 further uses onboardmemory 324 as well as small FIFO buffers 320, 322 on the FPGA 308 tobridge data streams between the processor on the computing device andthe RF front end 304. When receiving radio waveforms, digital signalsamples are buffered in on-chip FIFO buffer 320 and delivered into thesystem memory on the computing device when the digital samples fit in aDMA burst (e.g., 128 bytes). When transmitting radio waveforms, thelarge radio controller memory 324 enables implementations of the radiocontroller manager module 218 (e.g., FIG. 2) to first write thegenerated samples onto the radio controller memory 324, and then triggertransmission with another command to the radio controller 302. Thisfunctionality provides flexibility to the implementations of the SDRmanager module 218 for pre-calculating and storing of digital samplescorresponding to several waveforms before actually transmitting thewaveforms, while allowing precise control of the timing of the waveformtransmission.

Aspects of the present disclosure described further herein are directedto collaborative operations of software defined radios (SDRs) forpurposes of improving wireless communications between access points(APs) and stations, such as UEs, base stations, and the like. In someimplementations, such as in the case of UEs that are mobile electronicdevices, such as laptops, tablets, or cell phones, the stations may becontinuously moving to new positions with respect to stationary accesspoints for the wireless communication networks. In conventionalimplementations, the UEs perform handoff procedures with the accesspoints to maintain communications, but performing the handoff procedurescan take up processing resources from the UE that could be used forother purposes, and any errors that occur in the handoff procedures canresult in dropped network connections. Implementing SDRs in the accesspoints of wireless communications networks allows the access points tobroadcast PHY protocols for multiple transmission protocols as well asperform virtual handoff procedures between the access points that allowthe UEs to transition between multiple access point connections withoutperforming handoff procedures.

For example, in SDR implementations, functionality of some radiocomponents is achieved through execution of one or more softwareprocesses by the processing circuitry of the processor 202 rather thanthrough dedicated hardware components, which can be referred to assoftware defined components. For example, the filter components, anddigital signal processor may be software defined components of the SDR.In addition, some of the components of the RF front end 216 can also beexecuted as software defined components and/or are configured by thesoftware defined components. For example, the configuration of the ADCsof the receiver can be modified by control signals issued by theprocessing circuitry.

FIG. 4 is an exemplary diagram of a wireless communication system 400,according to certain embodiments. The wireless communication systemincludes access points (APs) 402, 404, and 406 which conduct wirelessdata transmissions with stations 410 and 412. The access points 402,404, and 406 can represent any hardware device that allow wirelessdevices to connect to a wired or wireless network via a communicationsprotocol, such as any of the IEEE 802.11 standards, 3GPP Long TermEvolution (LIE), LTE-Advanced (LTE-A), and any other wireless networkstandard. The access points may be included as circuitry associated witha base station, switch, router, user equipment (UE), and the like.

In some implementations, the access points 402, 404, and 406 include oneor more network layers, such as a network interface layer, media accesscontrol (MAC) layer, and physical (PHY) layer. The access points 402,404, and 406 can be connected to each other at the network interfacelayers via a backhaul network 408 that can be implemented as anETHERNET, fiber, backhaul wireless, or any other type of networkinfrastructure. The access points 402, 404, and 406 can transfer replicaPHY protocol data, MAC personality data, or any other type of datarelated to collaborative operations via the backhaul network 408. ThePHY layer of each of the access points 402, 404, and 406 includes a SDR,which is an implementation of the computing device 200. Like thecomputing device 200, the SDRs of the access points 402, 404, and 406include processing circuitry to perform the methods described furtherherein. The SDRs within the PHY layers allow the access points 402, 404,and 406 to simultaneously implement multiple communications protocolscorresponding to the stations 410 and 412. From the perspective of thestations 410 and 412, each of the access points 402, 404, and 406 canappear to be multiple access points or devices.

The stations 410 and 412 represent any hardware device that canwirelessly communicate with the access points 402, 404, and 406 via oneor more wireless communications protocols 414 and can include basestations or UEs such as mobile electronic devices, laptops, tablets, orcell phones. The wireless communication system 400 illustrated in FIG. 4is just one implementation, and other implementations can include anynumber of access points and/or stations based on system infrastructure,capacity, or station density.

In one implementation, the access point 402 implements a MAC/PHYcommunication protocol that corresponds to a communications protocol forthe station 410. Likewise, the access point 406 implements a MAC/PHYcommunication protocol that corresponds to a communications protocol forthe station 412. When the access point 402 detects another access pointthat is also able to communicate with the station 410 based onpredetermined connection criteria, the MAC layer of the access point 402can transfer replicated PHY protocol signals for the station 410 to theaccess point 404 via the backhaul network 408. Once the replicated PHYprotocol signal is received, the access point 404 can function as anidentical access point to access point 402 by implementing thereplicated PHY protocol so that the station 410 does not have to performhandoff procedures between the access points 402 and 404. Therefore, thereplicated protocol transfer achieved between access points 402 and 404can be performed so that the station 410 is unaware that there has beena change in the physical access point. Stated another way, the accesspoints 402 or 404 can communicate with the station 410 via a replicatedPHY protocol with unmodified communications parameters resulting in aphysical access point shift that is transparent to the station 410.

In addition, when the access point 404 connects to the station 410, theaccess point 404 sends a connection confirmation message to the accesspoint 402. Receiving the connection confirmation message from the accesspoint 404 provides an indication to the access point 402 that anotheraccess point has established a communication link with the station 410.Likewise, the access point 406 that is in communication with the station412 can also transfer a replicated PHY protocol signal to the accesspoint 404 so that the access point 404 can operate as an access pointfor both the station 410 and the station 412.

The predetermined connection criteria used to identify the access pointsto transfer the PHY protocol signals to can include a combination ofperformance-based and non-performance-based criteria. For example,performance-based criteria can include thresholds associated with signalstrength such as received signal strength indicator (RSSI), time ofarrival, GPS coordinates, motion prediction, and the like.Non-performance criteria can include load balancing between the APs. Forexample, if a signal strength for a signal received by the access point404 from the station 410 greater than a predetermined connectionthreshold or a motion prediction path indicates that the station 410will be inside a predetermined range of the access point 404 for atleast a predetermined period of time, the access point 402 can transferthe replicated PHY protocol signal for the station 410 to the accesspoint 404 via the backhaul network 408.

In addition, if the access point 402 no longer meets one or more of thepredetermined connection criteria for communicating with the station410, the access point 402 can transfer an entire MAC personality to theaccess point 404 via the backhaul network 408, and the station 410continues to operate as if the access point has not been modified. Inaddition, the access point 406 can also transfer a MAC personality tothe access point 404 when the access point 406 no longer meets thepredetermined connection criteria for communicating with the station412. In addition, when the access point 404 implements the transferredMAC personality for the station 410, the access point 404 sends a MACtransfer confirmation message to the access point 402. Receiving the MACtransfer confirmation message from the access point 404 provides anindication to the access point 402 that the access point 404 hasimplemented the MAC personality for station 410. In someimplementations, when the MAC personalities have been transferred fromthe access points 402 and/or 406 to the access point 404, the accesspoints 402 and/or 406 can continue to implement the replicated PHYprotocols for the stations 410 and/or 412 until the access points 402and/or 406 are unable to assist the access point 404 in communicatingwith the stations 410 and/or 412.

The access points 402 and/or 406 may terminate communications with thestations 410 and/or 412 when one or more predetermined disconnectioncriteria are met and the access points 402 and/or 406 have received theMAC transfer confirmation message from the access point 404 indicatingthat the MAC personality for the stations 410 and/or 412 have beenimplemented at the access point 404. The predetermined disconnectioncriteria may also include thresholds associated with a combination ofperformance-based and non-performance-based criteria such as RSSI, timeof arrival, GPS coordinates, motion prediction, load balancing, and thelike. In some implementations, threshold values for the predetermineddisconnection criteria may be equal to the threshold values for thepredetermined connection criteria. However, in other implementations,the threshold values for the predetermined disconnection criteria may begreater than or less than the threshold values for the predeterminedconnection criteria.

For example, a signal strength connection threshold may be greater thana signal strength disconnection threshold so that the access points 402and/or 404 transfer the MAC personalities to the access point 404 whenthe signal strength with the stations 410 and/or 412 fall below thesignal strength connection threshold but continues to transmit thereplicated PHY protocol for the stations 410 and/or 412 until the signalstrength falls below the signal strength disconnection threshold. As thestations 401 and/or 412 move through the wireless communication network400, the replica PHY protocols and/or MAC personalities are transferredbetween the access points 402, 404, and 406 so that the stations 410 and412 remain connected to at least one of the access points 402, 404, and406 without having to perform handoff procedures and without being awarethat the physical access point has been modified.

FIG. 5 is an exemplary flowchart of a handoff prevention process 500,according to certain embodiments. The handoff prevention process 500 isdescribed herein with respect to the wireless communication system 400but can also be implemented in any wireless communication system withaccess points that have SDRs in the PHY layers that are able torepresent multiple PHY protocols that correspond to the communicationprotocols of one or more stations within communication distance of theaccess points. In addition, the handoff prevention process 500 isdescribed with respect to interactions between the access points 402 and404 and the station 410 but can also be applied to the interactionsbetween the access points 404 and 406 and the station 412.

At step S502, one or more of the access points 402, 404, and 406establish or maintain a connection to a device, such as the station 410or station 412 via a PHY communications protocol that corresponds to thestation 410. For example, the access point 402 implements a MAC/PHYcommunication protocol that corresponds to a communications protocol forthe station 410. Likewise, the access point 406 implements a MAC/PHYcommunication protocol that corresponds to a communications protocol forthe station 412. In certain embodiments, the PHY communications protocolcan include protocols associated with any of the IEEE 802.11 standards,3GPP Long Term Evolution (LIE), LTE-Advanced (LTE-A) or any otherwireless network standard. The SDRs within the PHY layer of the accesspoints 402, 404, and 406 can implement more than one PHY communicationsprotocol in order to communicate simultaneously with more than onestation via more than one communications protocol.

At step S504, the processing circuitry of the SDR within the accesspoint 402 determines whether another access point can connect to thestation 410. The access point 402 detects another access point that isalso able to communicate with the station 410 based on predeterminedconnection criteria. The predetermined connection criteria used toidentify the access points to transfer the PHY protocol signals to caninclude a combination of performance-based and non-performance-basedcriteria. For example, performance-based criteria can include thresholdsassociated with signal strength such as received signal strengthindicator (RSSI), time of arrival, GPS coordinates, motion prediction,and the like. Non-performance criteria can include load balancingbetween the APs. For example, the processing circuitry of the SDR maydetermine that one or more predetermined connection criteria are metwhen a signal strength for a signal received by the access point 404from the station 410 is greater than a predetermined connectionthreshold or a motion prediction path indicates that the station 410will be inside a predetermined range of the access point 404 for atleast a predetermined period of time. If the processing circuitrydetermines that another access point can connect to the station 410based on the predetermined connection criteria, resulting in a “yes” atstep S504, then step S506 is performed. Otherwise, if it is determinedthat another access point is unable to connect to the station 410,resulting in a “no” at step S504, then the process returns to step S502.

If it is determined at step S504 that another access point can connectto the station 410, then at step S506, the access point 402 forwards areplica PHY signal to the other access point that is able to connect tothe station 410 via backhaul network 408, which is the access point 404according to one implementation. In some implementations, the MAC layerof the access point 402 can transfer replicated PHY protocol signals forthe station 410 to the access point 404 via the backhaul network 408.Once the replicated PHY protocol signal is received, the access point404 can function as an identical access point to access point 402 byimplementing the replicated PHY protocol so that the station 410 doesnot have to perform handoff procedures between the access points 402 and404 and is unaware that the physical access point has been transferred.In addition, when the access point 404 connects to the station 410, theaccess point 404 sends a connection confirmation message to the accesspoint 402. Receiving the connection confirmation message from the accesspoint 404 provides an indication to the access point 402 that anotheraccess point has established a communication link with the station 410.

At step S508, it is determined whether one or more of the predeterminedconnection criteria between the access point 402 and the station 410 arestill met. If it is determined that one or more of the predeterminedconnection criteria are still met, resulting in a “yes” at step S508,then the process returns to step S502, and the access point 402maintains connection with the station 410. Otherwise, if it isdetermined that t one or more of the predetermined connection criteriaare not met, resulting in a “no” at step S508, then step S510 isperformed. In some implementations, step S510 is performed if all of thepredetermined connection criteria are not met, but in otherimplementations, step S510 is performed if just one or more of thepredetermined connection criteria are not met.

If it is determined at step S508 that the access point 402 is unable tomaintain connection with the station 410, then at step S510, the accesspoint 402 transfers the MAC personality for the PHY protocol associatedwith the station 410 to the access point 404. When the MAC personalityis transferred to the access point 404 via the backhaul net work 408,the station 410 continues to operate as if the access point had not beenmodified. In addition, when the access point 404 implements thetransferred MAC personality for the station 410, the access point 404sends a MAC transfer confirmation message to the access point 402.Receiving the MAC transfer confirmation message from the access point404 provides an indication to the access point 402 that the access point404 has implemented the MAC personality for station 410. In someimplementations, when the MAC personalities have been transferred fromthe access point 402 to the access point 404, the access point 402 cancontinue to implement the replicated PHY protocols for the stations 410and/or 412 until the access points 402 and/or 406 are unable to assistthe access point 404 in communicating with the stations 410 and/or 412.

At step S512, it is determined whether one or more predetermineddisconnection criteria between the access point 402 and the station 410are met. The predetermined disconnection criteria may also includethresholds associated with a combination of performance-based andnon-performance-based criteria such as RSSI, time of arrival, GPScoordinates, motion prediction, load balancing, and the like. In someimplementations, threshold values for the predetermined disconnectioncriteria may be equal to the threshold values for the predeterminedconnection criteria. However, in other implementations, the thresholdvalues for the predetermined disconnection criteria nay be greater thanor less than the threshold values for the predetermined connectioncriteria.

For example, a signal strength connection threshold may be greater thana signal strength disconnection threshold so that the access points 402and/or 404 transfer the MAC personalities to the access point 404 whenthe signal strength with the stations 410 and/or 412 fall below thesignal strength connection threshold but continues to transmit thereplicated PHY protocol for the stations 410 and/or 412 until the signalstrength falls below the signal strength disconnection threshold. As thestations 401 and/or 412 move through the wireless communication network400, the replica PHY protocols and/or MAC personalities are transferredbetween the access points 402, 404, and 406 so that the stations 410 and412 remain connected to at least one of the access points 402, 404, and406 without having to perform handoff procedures.

If it is determined that one or more of the predetermined disconnectioncriteria are met, resulting in a “yes” at step S512, then step S514 isperformed. In some implementations, step S514 is performed if all of thepredetermined disconnection criteria are met, but in otherimplementations, step S514 is performed if just one or more of thepredetermined disconnection criteria are not met. Otherwise, if it isdetermined that t one or more of the predetermined disconnectioncriteria are not met, resulting in a “no” at step S512, then the processreturns to step S502, and the access point 402 maintains connection withthe station 410.

At step S514, the access point 402 may terminate communications with thestation 410 when one or more of the predetermined disconnection criteriaare met and the access points 402 have received the MAC transferconfirmation message from the access point 404 indicating that the MACpersonality for the station 410 has been implemented at the access point404.

FIG. 6 is an exemplary diagram of a multi-protocol wirelesscommunication system 600, according to certain embodiments. Themulti-protocol wireless communication system 600 includes an accesspoint 602 and a station 604 and is one implementation of the wirelesscommunication system 400. Like the access points 402, 404, and 406, theaccess point 602 can represent any hardware device that allow wirelessdevices to connect to a wired or wireless network via one or morecommunications protocols, such as any of the IEEE 802.11 standards, 3GPPLong Term Evolution (LTE), LTE-Advanced (LTE-A), and any other wirelessnetwork standard. In addition, the access points 602 includes one ormore network layers, such as a network interface layer, MAC layer, andPHY layer. Because of the PHY layer that includes a SDR, the accesspoint 602 can simultaneously implement different modem protocolsassociated with the station 604, such as a LTE PHY protocol and a WI-FIPHY protocol. The access point 602 also includes MAC personalities thatcorrespond to each of the PHY protocols.

Simultaneously implementing multiple PHY protocols within the accesspoint 602 allows the station 604 to seamlessly transition between theLTE connection and the WI-FI connection without performing any processesassociated with disconnecting or connecting to access points thatimplement just one of the communications protocols. For example, if thestation 604, is located outdoors, the station 604 may connect to theaccess point 602 via a LTE PHY protocol. As the station 604 moves insidea building, the access point 602 can make a transition to the WI-FI PHYprotocol connection so that as the device moves further into thebuilding where the LTE signal strength is weaker than outside thebuilding, the station 602 remains connected to the access point 602 viathe WI-FI PHY protocol.

FIG. 7 is an exemplary diagram of a multi-input, multi-output (MIMO)wireless communication system 700, according to certain embodiments. Thewireless communication system 700 includes access points (APs) 702 and704 which conduct wireless data transmissions with stations 706 and 708.The access points 702 and 704 can represent any hardware device thatallow wireless devices to connect to a wired or wireless network via acommunications protocol, such as any of the IEEE 802.11 standards, 3GPPLong Term Evolution (LIE), LTE-Advanced (LTE-A), and any other wirelessnetwork standard. The access points 702 and 704 may be included ascircuitry associated with a base station, switch, router, user equipment(UE), and the like. In some implementations, the access points 702 and704 include one or more network layers, such as a network interfacelayer, media access control (MAC) layer, and physical (PHY) layer. Theaccess points 702 and 704 can be connected to each other at the networkinterface layers via a backhaul network 710 that can be implemented asan ETHERNET, fiber, backhaul wireless, or any other type of networkinfrastructure.

The PHY layer of each of the access points 702 and 704 includes a SDR,which is an implementation of the computing device 200. Like thecomputing device 200, the SDRs of the access points 702 and 704 includeprocessing circuitry to perform the methods described further herein. Inaddition, the front ends of the SDRs of each of the access points 704and 704 have more than one antenna for conducting MIMO communications.For example, in the MIMO wireless communication system 700, the accesspoints 702 and 704 have two antennas each that are used to form 4×2 MIMOchannels to the stations 706 and 708 simultaneously. Locations of theaccess points 702 and 704 are separated by a distance of at least half awavelength (λ/2) to provide for MIMO signal decorrelation at thestations 706 and 708. The SDRs within the PHY layers allow the accesspoints 702 and 704 to modulate multiple frequencies at the same time inorder to transmit MIMO signals to the stations 706 and 708 whileachieving spatial diversity.

For example, the PHY at access point 702 modulates data on a frequencyF1 to be transmitted to the station 706 via spatial streams {0,1}. Theaccess point 702 also forwards coded data for the station 706, spatialstreams {2,3} frequency F1 to the access point 704 via the backhaulnetwork 710. The access point 704 then modulates the station 706 MEMOsignal, spatial streams {2, 3} on frequency F1. In addition, the accesspoint 702 applies a coding scheme to the spatial streams {0, 1, 2, 3}for the F1 MIMO signal transmitted prior to forwarding the spatialstreams {2,3} to the access point 704, and the coded signals are decodedat receivers of the station 706.

Likewise, the PHY at access point 704 modulates data on a frequency F2to be transmitted to the station 708 via spatial streams {0, 1}. Theaccess point 704 also forwards coded data for the station 708, spatialstreams {2, 3} frequency F2 to the access point 702 via the backhaulnetwork 710. The access point 702 then modulates the station 708 MEMOsignal, spatial streams {2, 3} on frequency F2. In addition, the accesspoint 704 applies a coding scheme to the spatial streams {0, 1, 2, 3}for the F2 MIMO signal transmitted prior to forwarding the spatialstreams {2, 3} to the access point 702, and the coded signals aredecoded at receivers of the station 708. The access points 702 and 704coordinate the transmission of the MIMO signals across the 4×2 MIMOchannels to ensure that the stations 706 and 708 successfully receivethe coded MIMO signals. In some implementations, the coordination of theMIMO signal transmission is performed based on predetermined timingspecifications and/or by exchanging data messages via the backhaulnetwork 710.

FIG. 8 is an exemplary flowchart of a MIMO modulation process 800,according to certain embodiments. The MIMO modulation process 800 isdescribed herein with respect to the MEMO wireless communication system700 but can also be implemented in any wireless communication systemwith access points that have SDRs with multiple antennas in the PHYlayers that are able to modulate multiple frequencies simultaneously inorder to transmit MIMO signals to multiple stations.

At step S802, the access points 702 and 704 modulate a first set ofspatial streams at predetermined frequencies. In some implementations,the predetermined frequencies correspond to operational frequencies forthe communications protocols, frequency band assignments for thestations and/or access points, and the like. For example, the accesspoint 702 modulates spatial streams {0, 1} to station 706 at a frequencyF1, and the access point 704 modulates spatial streams {0, 1} to station708 at a frequency F2.

At step S804, the access points 702 and 704 forward data for additionalspatial streams of the MIMO signal to the other access point 704 and 702via the backhaul network 710 to provide spatial diversity for the MIMOtransmission. The access point 702 forwards coded data for the station706, spatial streams {2, 3} frequency F1 to the access point 704. Theaccess point 704 then modulates the station 706 MIMO signal, spatialstreams {2, 3} on frequency F1. In addition, the access point 702applies a coding scheme to the spatial streams {0, 1, 2, 3} for the F1MIMO signal transmitted prior to forwarding the spatial streams {2, 3}to the access point 704. Likewise, the access point 704 also forwardscoded data for the station 708, spatial streams {2, 3} frequency F2 tothe access point 702. The access point 702 then modulates the station708 MIMO signal, spatial streams {2, 3} on frequency F2. In addition,the access point 704 applies a coding scheme to the spatial streams {0,1, 2, 3} for the F2 MIMO signal transmitted prior to forwarding thespatial streams {2, 3} to the access point 702.

At step S806, the access points 702 and 704 coordinate simultaneoustransmission of the MIMO spatial streams to the stations 706 and 708 onfrequencies F1 and F2 to ensure that the stations 706 and 708successfully receive the coded MIMO signals. In some implementations,the coordination of the MIMO signal transmission is performed based onpredetermined timing specifications and/or by exchanging data messagesvia the backhaul network 710.

FIG. 9 is an exemplary diagram of a collaborative beamformingcommunication system 900, according to certain embodiments. Thecollaborative beamforming communication system 900 includes accesspoints (APs) 902, 904, and 906 which can represent any hardware devicethat allow wireless devices to connect to a wired or wireless networkvia a communications protocol, such as any of the IEEE 802.11 standards,3GPP Long Term Evolution (LTE), LIE-Advanced (LTE-A), and any otherwireless network standard. The access points 902, 904, and 906 may beincluded as circuitry associated with a base station, switch, router,user equipment (UE), and the like, which conduct wireless datatransmissions with stations 932 and 940. Also, the access points 902,904, and 906 may be co-located or non-co-located. The collaborativebeamforming communication system 900 illustrated in FIG. 9 is just oneimplementation, and other implementations can include any number ofaccess points based on system infrastructure, capacity, or stationdensity. In addition, the collaborative beamforming communication system900 can perform any of the other processes discussed previously herein,such as the handoff prevention process 500 or the MIMO modulationprocess 800.

In some implementations, the access points 902, 904, and 906 include oneor more network layers, such as a network interface layer, MAC layer,and PHY layer. The access points 902, 904, and 906 can be connected toeach other at the network interface layers via a backhaul network 908that can be implemented as an ETHERNET, fiber, backhaul wireless, OF anyother type of network infrastructure. The access points 902, 904, and906 can transfer collaboration data, synchronization data, blockersignal data, or any other type of data related to collaborativeoperations via the backhaul network 908. In some implementations, thecollaboration data includes communication channel information for thestations 932 and 940. The PRY layer of each of the access points 902,904, and 906 includes a SDR, which is an implementation of the computingdevice 200. Like the computing device 200, the SDRs of the access points902, 904, and 906 include processing circuitry to perform the methodsdescribed further herein. The SDRs within the PHY layers allow theaccess points 902, 904, and 906 to adaptively respond to blocker signalsthat interfere with received signals by using collaborative beamformingto reduce interference from the blacker signals and increase the desiredsignal component by implementing SDRs in the access points 902, 904, and906 that are agile enough to transmit and/or receive any type of signalassociated with either of the stations 932 and 940.

When the access points 902, 904, and 906 communicate with the stations932 and/or 940, interference signals can be produced, which interferewith signals received by other stations, which can produce signaldistortions or masking of a desired signal. The interference signals canalso be referred to as blockers or blocker signals. For example, theaccess point 902 transmits signal 920 to the station 932 which producesa corresponding interference (blocker) signal 922 that is received bythe station 940, and the blocker signal 922 distorts desired signals,such as signal 930, that are received by the station 940. Likewise, whenthe signal 930 is transmitted by the access point 906 to the station940, corresponding blocker signal 928 is produced which distorteddesired signals, such as the signal 920, received by the station 932.

In some implementations, the access point 904 operates as a blockercancellation device and performs collaborative beamforming based onknowledge of signals 920, 922, 928, and 930 along with side informationto send cancellations signals 924 and 926 to the stations 932 and 940.For example, the purpose of the cancellation signals 924 and 926 is tocancel the interference associated with blocker signals 922 and 928. Inaddition, the cancellation signal paths 924 and 926 can be generatedbased on side information from the stations 932 and 940 to gainknowledge of signal paths from the access points 902, 904, and 906 tothe stations 932 and 940. In other implementations, the access points902 and 906 can also function as blocker cancellation devices. The SDRsin the PHY layer allow the access points to broadcast PHY protocols formultiple stations simultaneously so that one access point cansimultaneously transmit blocker cancellation signals associated withmultiple access points and/or stations.

In addition, the stations 932 and 940 can store channel informationassociated with each received signal. For example, the station 932 canstore channel information associated with the signals 920, 924, and 928,and the station 940 can store channel information associated with thesignals 922, 926, and 930. The channel information associated with thestation 932 can be communicated through a reverse-link communicationchannel to one or more of the access points 902, 904, or 906 and can becommunicated to the other access points 902, 904, or 906 via thebackhaul network 908. In addition, the access points 902, 904, and 906can perform reverse-link channel estimation based on transmissions fromthe stations 932 and/or 940 to the access points 902, 904, and 906. Theaccess points 904 functioning as the blocker cancellation device canadaptively modify the blocker cancellation signals 924 and 926 based onthe reverse-link channel information.

In one implementation, the access points 902, 904, and 906 can implementcollaborative beamforming to perform non-causal cancellation withcontrol channel, back channel information, and side channel information.In another implementation, the collaborative beamforming can beperformed on-the-fly. The collaborative beamforming can also be used toperform non-causal digital cancellation blockers.

FIG. 10 is an exemplary flowchart of a collaborative beamforming process1000, according to certain embodiments. The collaborative beamformingprocess 1000 is described herein with respect to the collaborativebeamforming communication system 900 but can also be implemented in anywireless communication system with access points that have SDRs that canadaptively respond to collaboratively cancel blockers in receivedsignals by transmitting blocker cancellation signals.

At step S1002, one or more of the access points 902, 904, and 906transmit signals to the stations 932 and/or 940. When the access points902, 904, and 906 communicate with the stations 932 and/or 940,interference signals can be produced, which interfere with signalsreceived by other stations, which can produce signal distortions ormasking of a desired signal. The interference signals can also bereferred to as blockers or blocker signals. For example, the accesspoint 902 transmits signal 920 to the station 932 which produces acorresponding interference (blocker) signal 922 that is received by thestation 940, and the blocker signal 922 distorts desired signals, suchas signal 930, that are received by the station 940. Likewise, when thesignal 930 is transmitted by the access point 906 to the station 940,corresponding blocker signal 928 is produced which distorted desiredsignals, such as the signal 920, received by the station 932.

At step S1004, the blocker signals 922 and 928 are detected by a blockercancellation device, which is the access point 904 according to oneimplementation. The access point 904 also determines informationassociated with the transmitted signals 920 and 930 as well as theblocker signals 922 and 928 in order to generate blocker cancellationsignals 924 and 926. In some implementations, the access point 904 cangenerate cancellation signal paths 924 and 926 based on side informationfrom the stations 932 and 940 to gain knowledge of signal paths from theaccess points 902, 904, and 906 to the stations 932 and 940.

In addition, the stations 932 and 940 can store channel informationassociated with each received signal. For example, the station 932 canstore channel information associated with the signals 920, 924, and 928,and the station 940 can store channel information associated with thesignals 922, 926, and 930. The channel information associated with thestation 932 can be communicated through a reverse-link communicationchannel to one or more of the access points 902, 904, or 906 and can becommunicated to the other access points 902, 904, or 906 via thebackhaul network 908. In addition, the access point 904 can performreverse-link channel estimation based on received transmissions from thestations 932 and/or 940 to the access points 902, 904, and 906. Theaccess points 904 functioning as the blocker cancellation device canadaptively modify the blocker cancellation signals 924 and 926 based onthe reverse-link channel information.

At step S1006, the access point 904 transmits the blocker cancellationsignals 924 and 926 to the stations 932 and 940, respectively. Theaccess point 904 performs collaborative beamforming based on knowledgeof signals 920, 922, 928, and 930 determined at step S1004 along withside information to send the cancellations signals 924 and 926 to thestations 932 and 940. In other implementations, the access points 902and 906 can also function as blocker cancellation devices. The SDRs inthe PHY layer allow the access points to broadcast PHY protocols formultiple stations simultaneously so that one access point cansimultaneously transmit blocker cancellation signals associated withmultiple access points and/or stations.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of this disclosure. For example, preferableresults may be achieved if the steps of the disclosed techniques wereperformed in a different sequence, if components in the disclosedsystems were combined in a different manner, or if the components werereplaced or supplemented by other components. Additionally, animplementation may be performed on modules or hardware not identical tothose described. Accordingly, other implementations are within the scopethat may be claimed.

The invention claimed is:
 1. An access point comprising: circuitryconfigured to implement one or more PHY communications protocols tosimultaneously communicate with one or more stations via communicationlinks on one or more wireless networks; communicate with additionalaccess points via a backhaul network; exchange collaboration data withat least one other access point of the additional access points via thebackhaul network, the collaboration data including media access control(MAC) personality data and replicated PHY protocol data that correspondsto a PHY communication protocol used by the access point to communicatewith at least a first station of the one or more stations, to switchcommunication with the first station from the access point to the atleast one other access point transparently to the first station;determine when the at least one other access point has established afirst communication link with the first station via a replicated PHYprotocol corresponding to the replicated PHY protocol data; and transferthe MAC personality to the at least one other access point when the atleast one other access point does not meet predetermined connectioncriteria for the first station.
 2. The access point of claim 1, whereinthe circuitry is further configured to transmit the replicated PHYprotocol data to one or more of the additional access points configuredto communicate with the first station based on predetermined connectioncriteria for the first station.
 3. The access point of claim 2, whereinthe predetermined connection criteria include performance-based ornon-performance-based connection criteria.
 4. The access point of claim3, wherein the performance-based connection criteria include at leastone of signal strength, time of arrival, positioning coordinates, motionprediction data, or PHY replica data.
 5. The access point of claim 3,wherein the non-performance-based connection criteria include loadbalancing criteria.
 6. The access point of claim 1, wherein thecircuitry is further configured to terminate a second communication linkwith the first station when one or more disconnection criteria are metand the at least one other access point has established the firstcommunication link with the first station.
 7. The access point of claim1, wherein the circuitry is further configured to simultaneouslyimplement the one or more PHY protocols via a software defined radio(SDR).
 8. The access point of claim 1, wherein the circuitry is furtherconfigured to forward received PHY protocol replicas to the additionalaccess points.
 9. The access point of claim 1, wherein the circuitry isfurther configured to communicate with the one or more stations via areplicated PHY protocol with unmodified communications parameters tocause a physical access point shift that is transparent to the one ormore stations.
 10. The access point of claim 1, wherein the circuitry isfurther configured to detect one or more blocker signals associated withone or more transmitted signals from the additional access points to theone or more stations.
 11. The access point of claim 10, wherein thecircuitry is further configured to simultaneously transmit blockercancellation signals to the one or more stations based on at least oneof information associated the one or more blocker signals or sideinformation.
 12. The access point of claim 11, wherein the circuitry isfurther configured to generate the blocker cancellation signals based onreceived channel information from the one or more stations via areverse-link communication channel.
 13. The access point of claim 12,wherein the circuitry is further configured to exchange the receivedchannel information with the additional access points via the backhaulnetwork.
 14. The access point of claim 1, wherein the circuitry isconfigured to: transfer the MAC personality data for the first stationto the at least one other access point via the backhaul network; andreceive, via the backhaul network, a transfer confirmation message thatthe at least one other access point has received and implemented the MACpersonality data for the first station.
 15. The access point of claim14, wherein to switch communication with the first station from theaccess point to the at least one other access point transparently to thefirst station includes the station communicating with the at least oneother access point with unmodified communications parameters resultingin a physical access point shift that is transparent to the firststation.
 16. An access point comprising: circuitry configured toimplement a PHY communication protocols to communicate with a mobileterminal via a wireless communication link; communicate with anotheraccess point via a backhaul network; transmit media access control (MAC)personality data and replicated PHY protocol data that corresponds to aPHY communication protocol used by the access point to communicate withthe mobile terminal to the another access point via the backhaul networkto cause the mobile terminal to switch from communicating with theaccess point to communicating with the another access pointtransparently without the mobile terminal performing a handoff processbetween the access point and the another access point; determine whenthe another access point has established a first communication link withthe mobile terminal via a replicated PHY protocol corresponding to thereplicated PHY protocol data; and transfer the MAC personality to theanother access point when the another access point does not meetpredetermined connection criteria for the mobile terminal.